Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-03-22
2001-08-14
Hofsass, Jeffery (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S609000, C340S618000, C340S644000, C200S182000, C200S186000, C200S187000, C200S190000
Reexamination Certificate
active
06275160
ABSTRACT:
FIELD OF THE INVENTION
The invention pertains to electronic timers used to help suppress transient signals. More particularly, the invention pertains to such timers used in waterflow detectors.
BACKGROUND OF THE INVENTION
Fire alarm systems have used a variety of technologies to attempt to provide audible or visible warnings of the existence of a fire condition to individuals in an area being monitored. In one known type of system, ambient condition detectors such as smoke, flame or thermal detectors are distributed in an area to be monitored. These units are often coupled via a communication link to a common control console or control panel.
The panel, in some instances, is capable of analyzing signals received from detectors to ascertain the presence of a fire condition. In other systems, a fire determination is made at the respective detectors and a signal indicative thereof is fed back to the control panel.
The above-described alarm systems are often used in combination with sprinkler systems. Known sprinkler systems incorporate sprinkler heads which are coupled to sources of fire suppressing liquids, such as water, or non-aqueous chemical suppressants.
The sprinkler heads are usually sealed with metals having relatively low temperature melting points. In response to the presence of heat from a fire, these metals soften and melt and release a fire suppressant.
Waterflow detectors have been used in such distribution systems to provide an indication that one or more of the sprinkler heads is delivering water to a portion of the region being monitored. Such waterflow detectors are disclosed, for example, in U.S. Pat. Nos. 4,782,333 entitled Waterflow Detector having Rapid Switching and 4,791,414 entitled Waterflow Detector. Both of the noted patents are assigned to the assignee hereof and are incorporated by reference herein.
Outputs from the waterflow detectors can in turn be used to directly energize alarm indicating visual or audible loads. Alternately, such signals can be coupled to an alarm system control panel for the purpose of providing additional warnings.
It is known that, from time to time, transient movement of water in a distribution system can occur in response to non-fire conditions. Such transient movement can be caused, by example, by intra-system water surges due to various causes.
Known water flow sensors often incorporate mechanical timers to incorporate a delay in an attempt to suppress such transience thereby minimizing false alarming. Known timers suffer from variability of the delays that are provided due to the mechanical timing mechanisms.
It would be desirable to provide highly repeatable transient suppressing delay intervals for use with waterflow sensors. Preferably such repeatable delay intervals could be achieved without introducing additional manufacturing complexity or manufacturing costs. It would also be desirable to be able to minimize power dissipation during no flow conditions.
SUMMARY OF THE INVENTION
A fluid flow detection unit incorporates a flow sensor which is coupled to a flow indicating switch having an open circuit state and a closed circuit state. A second switch having an open circuit state and a closed circuit state is also provided. The flow indicating switch and the second switch are both coupled to an electronic timer.
When the flow indicating switch exhibits a state indicative of the presence of flow, the electronic timer is enabled. When the timer generates an output, after a pre-set delay and if the flow indicating switch is still indicating fluid flow, then non-transient fluid flow is probably present. The delayed output from the timer can be used to close the second switch. In response to the two switches having changed state, energy can be provided to a load.
In one aspect of the invention, energy can be provided to an audible or a visual alarm indicating device. Alternately, or in addition, an alarm indicating signal can be provided to a control panel for an alarm system monitoring the region of interest.
In another aspect, the flow indicating switch can be coupled in series with the delay switch. In response to the flow indicating switch assuming a closed state, indicative of the presence of flow, a timer can be enabled.
Once the timer circuit times out, after its preset delay interval, and assuming that the flow indicating switch is still exhibiting a closed circuit state, the delay switch can be closed enabling a transfer of electrical energy from an input terminal, associated with the flow indicating switch, to an output terminal, associated with the delay switch. The electrical energy can in turn be transferred to a local alarm indicating unit and/or an associated alarm system.
In yet another aspect, each time the flow indicating switch goes from a closed, flow indicating state, to an open, no flow state, the timer circuitry can be reset. Further, the delay switch can be implemented as a latching switch which will continue to exhibit a low impedance state for as long as the flow switch indicates the presence of flow in the associated conduit. Finally, when in the no flow state, the timer circuit can be forced into a minimal power quiescent state.
When used with an alarm system, the flow indicating circuitry can be coupled to a power supply operable under the control of the alarm system control panel. The control panel can in turn switch the power supply from an inactive to active state.
Switching the power supply to an active state in turn energizes the switches associated with each of the flow sensors and simultaneously resets each of the latch-type, delay, switch to an open circuit state. Hence, subsequent to the fire condition having brought under control, the panel can de-energize and re-energize the waterflow detection circuitry thereby resetting each of the respective latching switches thereby open-circuiting each such circuit.
The flow indicating switches can be implemented as mechanical switches or as solid state switches without limitation. The latching, delay switches can be implemented as mechanical latching switches such as reed relays or latching relays without limitation. The timer circuitry can be implemented with solid state counters which can be preset to provide an output after a predetermined number of input pulses thereby producing a predetermined delay interval.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.
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patent: 5240022 (1993-08-01), Franklin
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patent: 5614067 (1997-03-01), Okazaki
patent: 5659300 (1997-08-01), Dresselhuys
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patent: 5705987 (1998-01-01), Doner
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patent: 5822819 (1998-10-01), Ferragut
Goins Davetta W.
Hofsass Jeffery
Pittway Corporation
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